SWA Depth?

[Sparky83]

Hello all,

Hopefully just a quick question really, i need to quote to install some cable to go around the outside edge of a large rounded driveway, it will be sunk into the ground but at what depth?

Ive looked online but see different depths quote, some 450mm some 600mm and some completely different.

Just want to make sure be any work starts.

Thanks,

Sparky83

 

[Octopus]

The glorious 7671 stikes again. IMHO its up to you to assess the ground, the likelihood of "digging" and decide for yourself.

Personally I would go for 600mm+

 

[chiplard]

At a sufficient depth to avoid damage.

Under a drive I would personally go for 18 inches. When under grass/borders 24 inches minimum.

Its your call really.

 

[Engineer54]

Hello all,

Hopefully just a quick question really, i need to quote to install some cable to go around the outside edge of a large rounded driveway, it will be sunk into the ground but at what depth?

Ive looked online but see different depths quote, some 450mm some 600mm and some completely different.

Just want to make sure be any work starts.

Thanks,


Sparky83

The standard ''direct buried'' depth is 600mm... If the cable run is to be close up to the edge of the driveway i would see no reason not to bury at 450mm. Even better if you lay a duct for this cable. But there's a lot more to laying direct buried cables than just the depth.


You need to make sure the base of the trench is stone free, as well as the top 30cm over the cable. always best to use soft sand for this. at the very least....sifted stone free soil!! Don't forget the warning marker tape either....

 

[pblec]

there isnt a depth for domestic in the regs,

i generaly do a quick risk assessment for the route side of a fence, under a lawn, between buildings, under a path, concreted in or through a vegitable patch down to run length.

trenching generaly costs about £30 per m at 600mm, labourer with a shovel is cheaper still. to date most of my customers are always trying to sve money so i've done the install and left a fair amount of 'slack' for them to bury later, i'm doing one this tue just like that straight across his lawn at 1 spade depth.

 

[Engineer54]

there isnt a depth for domestic in the regs,

i generaly do a quick risk assessment for the route side of a fence, under a lawn, between buildings, under a path, concreted in or through a vegitable patch down to run length.

trenching generaly costs about £30 per m at 600mm, labourer with a shovel is cheaper still. to date most of my customers are always trying to sve money so i've done the install and left a fair amount of 'slack' for them to bury later, i'm doing one this tue just like that straight across his lawn at 1 spade depth.

Make sure your indemnity insurance premiums are bang upto date, if you think that is a safe depth in a domestic garden. ....Or lay a very Thick walled duct.

 

[pblec]

fully understand where your coming from,

my risk assessment cable comes out of the house into an adaptable box down the wall into the ground 10m away summer house up the wall into another adaptable box. spade is 300mm deep, so after de-turf i would safely say in this instance 300-330mm is aceptable.

i would be more than happy to stand up in court and say this is perfectly ok especialy as i could of just laid it under the turf and been well within regulations

 

[Silly Sausage]

I've got to agree with Mr 54 on this one.
Someone hoofs their spade in, hits the cable, 'Oh &%$£'. They're are going to damage the outer sheath at least, leads to corrosion of the armour when they fill the hole back in, etc etc.
Under a lawn I'd have warning tape at 300mm then the cable at least another 100mm below that.

 

[chiplard]

fully understand where your coming from,

my risk assessment cable comes out of the house into an adaptable box down the wall into the ground 10m away summer house up the wall into another adaptable box. spade is 300mm deep, so after de-turf i would safely say in this instance 300-330mm is aceptable.

i would be more than happy to stand up in court and say this is perfectly ok especialy as i could of just laid it under the turf and been well within regulations

Would a court not argue that just under the turf is not at sufficient depth to avoid damage, if the cable got damaged!!!!

 

[Engineer54]

There are also other regulations you must meet, not sure these days what they come under, but you just might find that unlike the Reg's, they have teeth being of the statutory kind!!


I can tell you now, that a 300mm depth of a direct buried cable in a domestic garden won't meet Any regulatory or advisory regulation... I would think checking with the DNO's cable depths chart, (they used to produce one) will give you a good idea of the standard recognised burial depths of cable according to voltage bands.... None will be anywhere near your 300mm.

 

[Octopus]

Anyone got the DNO cable depth chart to hand?

One of my neighbours recently suffered a digger through their main supply cable and it was only about 8 inches (200mm for the youngsters) down.

The DNO sent the bill to the householder, who sent it on to the landscaper!

 

[Silly Sausage]

I'd love to have seen that!

 

[Engineer54]

Anyone got the DNO cable depth chart to hand?

One of my neighbours recently suffered a digger through their main supply cable and it was only about 8 inches (200mm for the youngsters) down.

The DNO sent the bill to the householder, who sent it on to the landscaper!

Tell them to send that bill straight back to the DNO, 200mm does not conform to any of their own cable depth rules/regulations....

 

[pblec]

yes you could, as i could also say if you burried it at 600mm i decided to plant potatoes so chose to double dig the plot and caught your cable. how goods your insurance? we can go back and forwards with this all night in the one i'm doing the homeowner has dug the trench will do the sanding, taping and backfilling so i doubt if he'll forget where the cable runs,

regs are there for a reason and if the IEE decided for domestic to give us a depth then it would be in it as its not its down to our own judgement.

next!

 

[Silly Sausage]

It's one those dodgy grey 7671 areas which we all hate the regs for.

But, by your own admission, you're laying a cable in open ground at just about the length of a spade blade.

Dig deeper & get your customer to dig deeper as well.